Restore Command of Your HUMMER’s Transmission
If your 2008-2010 HUMMER H3 is suffering from erratic shifting, getting stuck in gear, or throwing transmission codes, the culprit is often a failing Transmission Control Module (TCM). As a technician with over two decades of experience, I’ve seen firsthand how a faulty TCM can sideline even the most rugged vehicles. This T42 module, part number 24243921, is the definitive solution. It arrives pre-programmed to your vehicle’s specific VIN, eliminating the need for expensive dealership visits and ensuring a seamless, plug-and-play installation right out of the box.
Case Study: The Ghost in the Transmission
A customer brought in his ’09 H3 with a frustrating problem: it would randomly refuse to shift out of 2nd gear, but only after driving for 20+ minutes. The check engine light was intermittent. Other shops had replaced solenoids and flushed the fluid to no avail. After hooking up my scan tool and monitoring live data, I noticed the TCM was dropping communication when it warmed up—a classic sign of internal electronic failure. We installed one of our VIN-programmed T42 modules. The fix was immediate and permanent. This isn’t just a part; it’s a precise diagnostic solution that saves you from chasing ghosts and replacing perfectly good components.
Is Your HUMMER H3 Showing These Transmission Red Flags?
A failing TCM is the electronic brain of your transmission. When it malfunctions, it can cause a cascade of issues. Here are the most common symptoms I diagnose in the shop:
- ✔ Vehicle is stuck in “limp mode” (usually 2nd or 3rd gear) and won’t shift.
- ✔ Harsh, jerky, or delayed gear shifts that make driving uncomfortable.
- ✔ Check Engine Light or Transmission Warning Light is illuminated with Diagnostic Trouble Codes (DTCs) like P0700, P0750, or other solenoid-related faults.
- ✔ The transmission slips out of gear or fails to engage when shifting from Park to Drive.
- ✔ A noticeable drop in fuel economy due to inefficient shifting and torque converter operation.
- ✔ Complete loss of communication with the module, preventing the vehicle from starting or shifting at all.
A Straightforward Guide to Installation
One of the best features of this part is its accessibility. For the DIYer or professional mechanic, replacing the 2008-2010 HUMMER H3 TCM is a quick job that gets your vehicle back to perfect working order without special tools.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the Module: On the 2008-2010 HUMMER H3, the TCM is conveniently located in the engine compartment, specifically at the right-hand rear side.
- Disconnect and Remove: Carefully unclip the wiring harness connectors from the old module. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new VIN-programmed TCM into place and securely reconnect the wiring harnesses. Ensure the clips click into place.
- Final Steps: Reconnect the battery terminal. While our programming handles the critical setup, it’s always best practice to use a standard OBD2 scan tool to clear any stored fault codes from the vehicle’s memory.
Verified Vehicle Compatibility
This T42 TCM is a direct-fit replacement for a wide range of General Motors vehicles equipped with 4-speed automatic transmissions like the 4L60E and 4L65E. While it is guaranteed to fit your 2008-2010 HUMMER H3 TCM, it also fits other models. This module is interchangeable with part numbers 24243921, 24252114, 24234503, and more.
- HUMMER H3 (2008-2010)
- Chevrolet Silverado & GMC Sierra (2007-2013)
- Chevrolet Tahoe & GMC Yukon (2007-2009)
- Chevrolet Colorado & GMC Canyon (2008-2012)
- Chevrolet Impala (2006-2011)
- Chevrolet Express & GMC Savana (2006-2014)
- And many other GM cars, trucks, and SUVs.